Conventionally, call contract information (hereinafter, referred to as “subscriber information”) such as a phone number, user ID, and calling rate, is stored in the memory of a mobile phone terminal. In making a call, an exchange receives a notification about the phone number, and authentication of the subscriber and billing process are performed by using this phone number.
In recent years, there has been developed a system which employs a subscriber information card referred to as SIM (Subscriber Identity Module) card which stores the subscriber information in an IC memory card. The SIM may also be referred to as UIM (User Identity Module). This system is configured such that the subscriber information is not stored in the mobile phone terminal in itself and calling is disabled with the mobile phone terminal alone. By mounting a SIM card provided by contract onto the mobile phone terminal, the subscriber is allowed to use the mobile phone terminal with the phone number that is recorded in the card. With the configuration above, even when the mobile phone terminal is replaced with a new one, the SIM card can be mounted on the new mobile phone terminal, thereby allowing the user to make a call immediately with the new one. It is further possible to record on the SIM card, a list of phone numbers of callees in addition to the subscriber information.
On the other hand, the mobile phone terminal is growing and expanding in functionality, installing multifunction such as a standby screen, ringing tone replay, Web browsing, E-mail, built-in electronic camera, moving picture player/recorder, scheduler, execution of downloaded applications such as games. Therefore, a flash memory in the mobile phone, which is a non-volatile memory being rewritable, is designed to store a large volume of data, such as address book data including phone number and mail address, E-mail data, bookmark of browser, photo, sound, moving picture, downloaded application data, schedule data, and various set-up data.    Patent Document 1: Japanese Patent Laid-Open Publication No. 2002-57807